The quasifree p+n→d+η reaction cross section has been measured at the threshold using 1295 MeV protons in the CELSIUS storage ring and an internal cluster-jet deuterium target. The kinematics is chosen such that the target proton can be assumed to be a spectator. The Fermi momentum of the target neutron is used to extract the energy dependence of the cross section by reconstructing the kinematics on an event-by-event basis. The data cover excess energies from threshold to 10 MeV in the center of mass of the final dη system. Approaching the threshold the cross section is enhanced compared to what is expected from phase space. This behavior is typical for a strong final-state interaction.
Cross section as a function of the C.M. excess energy.
Measurements of elastic photoproduction cross sections for the J / ψ meson from 100 GeV to 375 GeV are presented. The results indicate that the cross section increases slowly in this range. The shape of the energy dependence agrees well with the photon-gluon fusion model prediction.
Data supplied by V. Paolone.
Cross section data using Bethe-Heitler event normalization.
Cross section data using the Beam Gamma Monitor normalization.
The production of neutral strange particles (K0, Λ) inp Ar,pXe and\(\bar p\)Xe collisions at 200 GeV is investigated in the NA5 experiment using a streamer chamber at the CERN SPS. Results are presented on inclusive cross sections, average multiplicities, and on rapidity and transverse momentum distributions of neutral strange particles.
No description provided.
No description provided.
No description provided.
With a sample of about 2000( γ + γ ′+ γ ″) events observed in π-W interactions at 286GeV/ c , the ratio ( γ ′+ γ ″)/ γ =0.51±0.07, the branching ratio times the inclusive total cross section Bσ =(386±17±85) pb per W nucleus, as well as the differential cross sections in χ F and p T have been measured. These results are compared with previous data obtained with the same apparatus at a lower beam momentum (194 GeV/ c ). Both data sets are compared with a theoretical calculation (“duality model”) which also allows one to extract the shape parameter β g of the gluon distribution in the pion. β g is found to be 2.3 −0.3 +0.4 (stat.) −0.5 +0.1 (syst.).
No description provided.
Inclusive charged-current interactions of high-energy neutrinos and antineutrinos have been studied with high statistics in a counter experiment at the CERN Super Proton Synchrotron. The energy dependence of the total cross-sections, the longitudinal structure function, and the nucleon structure functionsF2,xF3, and\(\bar q^{\bar v} \) are determined from these data. The analysis of theQ2-dependence of the structure functions is used to test quantum chromodynamics, to determine the scale parameter Λ and the gluon distribution in the nucleon.
ABSOLUTE FLUXES HAVE NOT BEEN MEASURED. NORMALISED TO OLD RESULTS.
STUCTURE FUNCTIONS ARE EVALUATED ASSUMING R=SIG(L)/SIG(T)=0.1 AND M(W) IS INFINITE. NO CORRECTION FOR FERMI MOTION APPLIED. ERRORS ARE STATISTICAL AND SYSTEMATIC POINT-TO-POINT ERRORS. IN ADDITION OVER-ALL SCALE ERROR OF 6 PCT. FOR F2 , 8 PCT. FOR XF3.
STUCTURE FUNCTIONS ARE EVALUATED ASSUMING R=SIG(L)/SIG(T)=0.1 AND M(W) IS INFINITE. NO CORRECTION FOR FERMI MOTION APPLIED. ERRORS ARE STATISTICAL AND SYSTEMATIC POINT-TO-POINT ERRORS. IN ADDITION OVER-ALL SCALE ERROR OF 6 PCT. FOR F2 , 8 PCT. FOR XF3.
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